It's a Spot 2 Tracker. A little orange device with a GPS and the capability to link into the globalstar satellite network. Actually it doesn't do very much: Get the coordinates and broadcast them. That's it. No two-way communication >> just a one-way street. Attached to that data-burst is one of four flags depending on which button you pressed:
- OK / Check in Message
- Custom Message
- HELP / I need assistance
PLB. If the Spot doesn't get a GPS fix your doomed ...or at least it can't tell anyone where you are. Also the uplink isn't that reliable. And finally it's not exactly cheap: The Spot is around 150 USD plus another 150 USD / year subscription fee. If you live in Oz add another 40 USD shipping.
So why bother and not just buy a cheap PLB? Yo can get the McMurdo Fast Find 210 for 250 USD! The storage life of the battery is 5 years and no additional fees or charges. Well here's the thing: A PLB is for emergencies only. You might know that you are ok and don't need help but here's a shocker: You're not alone on this planet and some of these people might care about you: They want to know too! Now it's just a button on the Spot.
If you want to have a super-reliable emergency beacon go for a PLB
If you just want to ease the minds of the loved ones while you're out in the bush* go for a Spot.
If you have too much money, buy both.
Just remember SAR is much more fun without the search - especially if you're the one to be rescued!
* = The Spot is quite pointless in Europe >> mobile coverage is really good: All the way up to the top of Mont-Blanc I had 3G and tweeted along the way.